Jordin Canada added 12 points, making all eight of her free throws, including six in the final 39 seconds, and Nirra Fields had 10 for the Bruins (5-7). McKenzie Calvert had 16 points and Kaneisha Horn 12 for the Trojans (8-4).
UCLA led 32-24 at the half, but USC scored the first 10 points of the second half, taking the lead on Horn's layup at 15:32.
Caldwell's jumper at 14:52 tied the score and Monique Billings scored to put the Bruins up for good at 13:37. UCLA made nine of 10 free throws in the second half while USC made only five of 11 for the game.
The Trojans shot only 33%, including three for 22 behind the arc, and finished 21 points below their average.